First time HTPC advice

Hopefully I can get some help here deciding what to get for my first HTPC. Currently I'm running XBMC off my laptop w/ android remote, and I'm looking to upgrade to a dedicated machine that I’ll use only for XBMC.

I’ve read through a lot of threads and learned a lot, but it’s all become very confusing and it seems to be very confusing and/or outdated.

Let me start with what I want from my HTPC. I’m looking at a group 4 or 5 machine. Right now I just play movies over HDMI, but I don’t want to buy a machine and then decide that I want to start streaming Neflix, so I’d like the hardware to be suitable in case I want to go that route in the future. I don’t need or want a blu-ray player, as I already have one. Also the quieter the machine/lower power required, the better (naturally).

I do want to be able to turn the computer on and off via remote, or at least be able to put the computer to sleep/wake via remote. The more seamless that process is, the better. The discussion thread on this is ridiculously confusing and I don’t want one of the options involving self-modding a case or anything like that.

Should I go Windows? OpenELEC? XBMC Live? I’ve only ever used XBMC on my laptop running windows, but this machine will only be used to play media from an attached external drive.

I’d prefer not to build a custom machine, because I’m not that well versed in computer building, don’t have a ton of time to devote to learning, and frankly I like the form factor of a lot of nettops available.